Questions tagged [function-construction]
For questions on writing functions (pure or using Set/SetDelayed) for any purpose, including the features that may be incorporated in those functions, such as options, patterns and conditions.
2,313
questions
2
votes
2
answers
178
views
Sorting a List Based on a Given Order
Suppose I have the following input:
input={{1, 2, 3}, {-2, 4, 6}, {-1, 3, 6}}
How can I sort it according to this list:
...
- 2,293
0
votes
1
answer
49
views
Equivalent Uses of SetDelayed Result in Different Results When Defining an Existing Variable
I have the following expression.
...
2
votes
0
answers
77
views
How to write 2D finite volume solver in a functional approach?
I'm solving 2D poisson problem of a finite volume problem using TDMA.
The solution of the problem is given:
\[Phi][x_, y_] := x^2 y + x y^2 + 1
The definitions are ...
- 41
2
votes
0
answers
53
views
Argument value loss using Listable C-Compiled Function
In my recent studies, I have come across a very strange anomaly with C compiled functions. When I call a function that has the 'Listable' attribute while global variables are accessed through ...
3
votes
1
answer
195
views
Test whether an expression contains a particular pattern
How to test whether an expression contains a particular pattern ?
I made a function for myself that tests whether an expression contains Plus or not.
...
- 3,529
0
votes
1
answer
79
views
When running code to compute a sequence, loop variable gets set to a constant
I would like to write Mathematica code to read in a list of sequences, and print the sequence definition ($a_n$), along with the sequence evaluated at a few values of $n$.
...
- 1,939
1
vote
1
answer
79
views
How to convert a function with named arguments to a pure function?
A function is defined with named arguments. How can this function be converted to a pure function that uses slots (#). As a simple example, how can the following:
<...
- 225
0
votes
1
answer
34
views
Properly defining functions after they have been used in expressions [closed]
I am having trouble with how functions behave when defined, after they have been used in an expression. More specifically, I start with an expression of the form:
...
0
votes
1
answer
50
views
How to perturb data along a midline?
Consider the following data, which can be obtained here
ListLinePlot[data, Frame -> True]
I want to perturb the previous data around a defined midline, which ...
- 4,362
4
votes
2
answers
80
views
Filtering out function pairs with domains lying on one side of an intersection point
I have a list of pairs of functions that intersect at one point, as shown in the image. I am attempting to remove pairs where the domain of both functions in the pair lie on one side of the ...
- 2,822
2
votes
1
answer
50
views
Using the result of Solve as a function of parameters
I am trying to find b2 maximising a function I named 'EG1EUB'. And 'EG1EUBb2' is the frist order condition. Based on my understanding, Solve gave me a single solution saying that b2 is the second root....
- 45
6
votes
1
answer
127
views
How to keep lines on boundary or inside a region?
This post is related to one of my previous posts. My goal is to keep only the lines that fall on the boundary (2, 8) or inside the region ...
- 2,822
0
votes
0
answers
36
views
Syntax highlighting like Function?
I'd like to define a symbol that behaves similar to Function. Specifically, I want to define a new symbol symmetricFunction that ...
- 2,923
6
votes
1
answer
112
views
Sort the nested list by the sublist content; sublists of different lengths
I would like to write the function NewSort function that sorts a list of sorted sublists, basing first on the canonical ordering of subsequent sublist elements. In ...
- 73
1
vote
0
answers
60
views
How to make the thickness of the line constant?
I created this code based on a previous post, with some modifications to plot a line with a 30-degree slash. It partially works, but the thickness of the slash varies from line to line. How can I make ...
- 2,822
0
votes
0
answers
37
views
Nest n-times a multi-variable function with only one of the variables being updated with previous function value
I have a function y1 of three variables, x, y, and z. (y1 also depends upon f1 defined previously). I would like to Nest or interate, such that on the nth iteration, the y1's 3rd variable, z, will be ...
- 33
3
votes
2
answers
256
views
How to write a function that performs two operations? [closed]
I am solving an entry-level exercise to practice on writing my own functions in Mathematica.
I want to build a function that accepts a matrix of size larger than 2×2.
The function will replace the {1,...
- 353
3
votes
0
answers
51
views
How can one automatically arrange the connections of a circuit with as few crossings as possible, given a set of edges?
Here are two functions to create symbols of dc voltage source and a resistor.
...
- 2,822
2
votes
1
answer
80
views
Defining function for decimal value k[0.5+0.5]
k[1 + 1] = 2;
k[1 + 0.5] = 1.5;
k[0.5 + 0.5] = 1;
{k[2], k[1.5], k[1]} // TableForm
2
1.5
k[1]
Can you explain this phenomenon? I think the output should be
...
- 3,529
5
votes
3
answers
275
views
Distribute arguments over a function in all ordered combinations
I'm looking for a function that can do this
...
- 630
1
vote
2
answers
77
views
Would it be slower to place function definitions inside another function definition?
Will it be slower to place functions' defintions inside a main function? I usually do that if the subfunctions are short.
However, with a long subfunction I usually place it outside as I think that ...
- 273
0
votes
1
answer
69
views
Tell Mathematica how to //Expand a function
I have a function DP that takes two arguments, that is linear in both, i.e. DP[a,b+c] = DP[a,b] + DP[a,c]. I am using the following:
...
- 695
0
votes
0
answers
38
views
Define regular function as difference of two piecewise functions
Consider a piecewise smooth function,
...
- 1,317
3
votes
3
answers
180
views
Building A Function Using Constants From a List
I want to build a function of the form
$f(t)= C + \sum_i A_i*Sin(f_i*t+\phi_i)$
Where $(A_i,f_i,\phi_i)$ are amplitudes, frequencies and phases that I have stored in a text file. Here is my attempt:
<...
- 43
9
votes
3
answers
570
views
2
votes
2
answers
105
views
How to gather functions which intersect at the same point?
How to gather functions which intersect at the same point (real solution)?
func = {2 x, x^2 + 1, (x^3 + 3)/2};
For example, with the list of functions above I ...
- 2,293
2
votes
1
answer
118
views
Using the Apply construction
I am puzzled about the use of Apply (@@). Consider
g = t;
g1 = Function @@ {t, g}
g2 = Function[t, g]
Why does g2 differ from g1? I had thought they would be ...
- 213
1
vote
2
answers
63
views
Function defined through conditional pattern and derivative
If I define a function through a conditional pattern, its derivative is not defined in the whole domain of the original function...
Minimal code to reproduce : for instance, I define
...
- 301
3
votes
3
answers
392
views
3
votes
1
answer
71
views
How to delete edges from a graph with some condition?
I want to delete an edge and its reversed edge from a graph (if they exist in the graph).
It would be OK to use EdgeDelete[g, {edge, Reverse[edge]}] if these two ...
- 273
3
votes
3
answers
67
views
Sort a list using a scoring list with Switch [duplicate]
I have a minimal working example (MWE) list called listToSort that is a list of string triplets:
...
- 9,747
1
vote
1
answer
94
views
Define a function on a MeshRegion
This looks like a simple question with the answer to be easily found, but unfortunately I could not find it either on the web or in the documentation browser.
Let us assume we have a MeshRegion ...
- 151
5
votes
5
answers
2k
views
How can I ignore an argument?
I made some code (attached below). It is meant to make a list of random numbers that is not divisible by some value k.
I wish to be able to not enter a value k, and have the code run regardless. It ...
- 125
3
votes
3
answers
379
views
How to make a function take another function as an input?
I am quite new to mathematica, and I simply want to know how to make a custom function, take another arbitrary function as an input.
I have attached code that shows what I am trying to accomplish (...
- 125
15
votes
4
answers
2k
views
Automating interesting ways to write 2023
Inspired by Interesting ways to write 2023, I was wondering if there are ways to automate the search for results using MMA.
I tried
...
- 2,570
2
votes
1
answer
52
views
Failing to define a function? [duplicate]
I am trying to define a function and it apparently is not working. Here is my small working example:
...
0
votes
1
answer
61
views
Create a function that can assign values to different variables in Mathematica
Here I am trying to create a function that can assign values to different variables in Mathematica.
Assume the function
f[a _, b _, c _];
x1 = a;
x2 = b;
x3 = c;
...
- 51
2
votes
3
answers
80
views
Constructing a function that returns two distinct values by Mathematica
I'm trying to enter a function in Mathematica that can take two inputs, a, and b, and return two outcomes based on those two numbers.
I will assume the name of this function as
Resultsf[a _,b _]
the ...
- 51
1
vote
1
answer
90
views
2
votes
2
answers
49
views
Is it possible to combine a default value in a function definition with type-checking, in case the optional parameter is actually given in a call?
1.) In a function definition, e.g.
...
- 2,778
0
votes
1
answer
39
views
Piecewise function with form determined by current value
I would like to create a piecewise function that determines the dynamics of a variable $x_t$ as follows:
Given a starting value $x_0$ and a parameter $\hat{x}$:
...
- 321
2
votes
2
answers
73
views
How does one pass an arbitrary expression (or expressions) to a function to later be evaluated? [closed]
This isn't my exact use case, but I think the answer will still be applicable to what I'm doing. I essentially want to create a function with which I can pass an expression (or list thereof), certain ...
- 23
2
votes
2
answers
161
views
Returning an InterpolatingFunction
I am trying to write a function using Block that generates an InterpolatingFunction and then generates a second InterpolatingFunction that is a function of the first. I can return and use the first ...
- 213
1
vote
2
answers
106
views
How to have index of summation equal to all $n$-tuples $\left(b_i\right)_{i\le n}$ with $\sum ib_i = n$ and $b_j$ fixed?
Let $T_n$ denote the set of $n$-tuples $\left(b_1, \ldots, b_n \right)$ of non-negative integers such that $$\sum_{i=1}^{n}ib_i=n.$$ I am trying to simplify the sum (whose indicies depend solely on $n,...
- 273
1
vote
1
answer
90
views
How to do a 5x5 system using Cramer's rule? [closed]
I need to know how to do a 5x5 system using Cramer's rule.
1
vote
1
answer
128
views
A square board of size n*n [closed]
I would like to Randomly generate n^2 natural numbers in an interval from 1 to n. Then consider placing each number on the cell with the same number (you can imagine the board numbered naturally, row ...
- 93
4
votes
1
answer
124
views
Is there analogy of function MapIndexed (Map) for Nest?
We have Map and its upgraded variant MapIndexed.
Is there analogy for Nest? I know there is ...
- 5,915
0
votes
0
answers
41
views
How to assign a variable in mathematica to just the output of an expression?
So, say I wanted to assign a function J[x_, y_] :={D[system, x], D[system, y]}//Transpose where system is some system of ...
2
votes
1
answer
60
views
Print out how many times to calculate the sum of the squares of its digits until answer is 1 or 4
I am trying to write a recursive function, toscare1[], that takes as parameter a positive natural number. Then calculate the sum of the squares of its digits, thus creating a new number; then, we ...
- 93
0
votes
0
answers
41
views
Derive a function and then make a fast version for execution
I would like to derive a (complicated) equation of motion and integrate it efficiently numerically. I can do this "by hand" by copying the resulting function in a new function and then ...
- 213